Bao Yu Wang

Numerical Simulation and Experiment of Hot Roll Forming Large Module Gear

To compare with the other gear manufacturing methods, the hot roll forming process is applied in forming large module gear. The hot gear rolling theory is realized by modeling in Solidworks and Deform-3D, the finite element model (FEM) that coupled deformation and heat transfer was established, and the FE model velocity boundaries were set by converting the workpiece rotation into the revolution speed of the roller. The total displacement of metal flow, folding angel of teeth, effect strain and the temperature distribution of the part were obtained in the whole process of hot gear rolling, also the rolling force was predicted by simulation. The simulation results reveal the forming mechanism, and the rolling experiments were carried out with self-designed rolling mill, which verify that the hot roll forming large gear is feasible.

The Influence of Process Parameters during Hot Stamping of AA6111 Aluminum Alloy Sheet

The AA6111 aluminum alloy sheet is widely used in auto-body manufacture. It can make use of good plasticity under high temperature to form more complex parts by using the hot stamping. The influence of process parameters in hot stamping of AA6111 aluminum alloy sheet is investigated through numerical simulation in this paper, including blank holding force (BHF), friction coefficient, stamping velocity and initial forming temperature. Finally forming defects of numerical simulation are verified through the hot stamping experiments. The results show that it can effectively avoid wrinkling and fracture by controlling the BHF, good lubricant is in favor of forming and numerical simulation can accurately predict forming defects to guide the production.

Analysis of Square Billet Cross Wedge Rolling Process Using Finite Element Method

The aim of this paper is to determine whether the train axle cross wedge rolling(CWR) using square billet as blank is available or not. Based on numerical simulation software DEFORM-3D, we built the finite element model. And the whole forming process was simulated successfully. The stress and strain distributions of workpiece in the process were analyzed. The effect of forming angle, stretching angle and billet size on rolling force was investigated, then determined the proper process parameters. The differences between the round billet rolling and the square billet rolling were obtained by comparing the tangential, axial and radial forces during the rolling process. The studied results show the availability of using square billet as blank in train axle CWR and provide important realistic meaning and application value.

The Numerical Simulation of GH4169 Alloy during Cross Wedge Rolling

The metal microstructure of a product formed by cross wedge rolling (CWR) has much effect on the comprehensive properties of the final product. The microstructure model of GH4169 alloy was programmed into the rigid-plastic finite element software DEFORM-3D by the secondary development in this paper, so the microstructure evolution during the CWR process can be simulated. The finite element model (FEM) that coupled deformation, heat transfer and microstructure evolution was established. Based on the model, the evolution of microstructure of GH4169 alloy in the process of CWR was realized with the simulation. The strain, strain rate, temperature and the distribution of grain size of the part were obtained in the whole process of CWR. The simulation results show that the dynamic recrystallization is the main grain refinement mechanism for the CWR process and the grain refining effect of the workpiece during the CWR process is remarkably.

A Material Selection Criterion for Hot-Stamping Dies

Hot-stamping technology applies hot-stamping dies to the forming and quenching of austenitized high-strength steel plates to produce super-high-strength parts. To carry out these forming and quenching functions, the hot-stamping dies must be able to withstand shock and high-temperature friction under harsh working conditions, and hence high-quality die materials are necessary. However, since the material performance requirements of hot-stamping dies have not been standardized, and special die materials have not been developed, the choice of materials is based on improving the safety coefficient, which leads to material waste and increased costs. In this article, the performance of the hot-stamping process is analyzed to obtain the main resistance indices and a material selection formula for hot-stamping dies, enabling the selection of hot-stamping die materials to be quantified, and thereby establishing a scientific basis for the selection process.

A Method to Optimize Aluminum Alloy Door Impact Beam Stamping Process Using NSGA-II

The process parameters of aluminium alloy hot stamping produce an importantly effect on production forming quality. In the case of a door impact beam inside the car doors, the fi-nite-element model of aluminium alloy hot stamping is set up. Based on the model, the forming quality is investigated under usual process condition. Using the Latin hypercube method, we sampled the data points from design space of process parameters. Data points are imported into finite-element model to calculate the forming quality indices. According to their responding values, the quadratic response surfaces between process parameter inputs and forming quality indices are initialized. By optimized the response of the process parameters exercising multi-objective genetic algorithm—NSGA-II (non-dominated sorting genetic algorithm), the Pareto combinations of blank hold force and stamping velocity are obtained. Finally, by comparison with the results of stamping trial and numerical simula-tion, it is concluded that the finite-element model can be used to predict forming defects and is consistent with actual condition. Thus the optimization method is feasible.

Forming Load Calculation of Hot Precision Forging of Cylindrical Gears

The Tooth Impact Factor was defined and introduced into the formula of forming load of closed-upsetting. Thus the formula for calculating the forming load of hot precision forging of cylindrical gears was put forward. The equation for the Tooth Impact Factor was fitted using the data from FE simulation of forging process in which gears with different modules were forged. Some forging tests for gears were conducted and the forming load was measured to ensure the validity of the formula. The tests also revealed that the formula is suitable for forming load calculation of hot precision forging of both spur and helical gears in a wide size range.

Modeling of Phase Transformation for TA15 Titanium Alloy During Heat Treatment

In this paper a phase transformation model with the temperature has been used to predict the percentage of phase at different temperature for TA15 titanium alloy during heat treatment. Heat treatment tests were conducted on TA15 samples at different temperatures ranging from 850°C to 1000°C. The material parameters were determined by using the test results and an Evolutionary Programming (EP)-based optimization method. Good agreements between the experimental and computed results were obtained.

Study on 4Cr9Si2 Martensitic Heat-Resistant Steel in CWR

4Cr9Si2 Martensitic heat-resistant steel is inlet valve and the exhaust tappet materials. This paper is based on the constitutive relationship of 4Cr9Si2 Martensitic heat-resistant steel obtained by isothermal compression; a finite element model of Cross Wedge Rolling was build up for 4Cr9Si2 Martensitic heat-resistant steel. In the model the heat conduction between billet and the die, the convection of heat transfer, and the thermal conversion of plastic work and friction work were taken in account, the value of damage was obtained in the rolling and central porosity was analysis. Then verify the correctness of the FEM and feasibility of simulation results by the experiment

Effect of Process Parameters on the Temperature of 4Cr9Si2 Martensite Refractory Steel during CWR

Based on the constitutive relationship of 4Cr9Si2 martensite refractory steel obtained by Gleeble-1500 hot simulation isothermal compression, a finite element model of Cross Wedge Rolling was build up for 4Cr9Si2 Martensite and the heat conduction, convection, plastic work and friction work were taken in account in the model. The forming process of 4Cr9Si2 martensite refractory steel by cross wedge rolling was simulated by means of DEFORM-3D software. The influence regularities of temperature of rolling process parameters were obtained: temperature rise rapidly result from plastic work and friction work in the cross-section at the process of rolling, with the completion of rolled piece cross-section, temperature descending due to heat conduction and radiation with atmosphere. The rolled piece temperature difference decrease with rolling speed and die preheat temperature increasing, the billet heating temperature is little for rolled piece temperature difference compared with rolling speed and die preheat temperature.